1. Field of the Invention
This invention relates to an actuating mechanism mechanically actuating responsive members such as brake shoes of a drum brake by rotating an actuating lever, and particularly to an apparatus and method for connecting an operating cable to an actuating lever.
2. Description of the Related Art
A typical apparatus is, for example, employed in a brake cable connecting apparatus designed to connect the brake cable to the brake lever as a component of a mechanical actuating mechanism for a drum brake device.
Normally, the mechanical actuating mechanism has a mechanism in which one brake shoe, as one responsive member, engages with one end of a strut and the other brake shoe, as another responsive member, engages with the brake lever in the vicinity of a pivot section between the brake lever and the other end of the strut. A cable end nipple on the brake cable is connected on the free end of the brake lever in the cable operating direction; and the brake lever and the strut rotate relative to each other around the pivot section of the same upon operating the brake cable, so that both brake shoes are urged to separate apart from each other.
An available structure of the brake cable connecting apparatus, connecting the cable end nipple on the free end of the brake lever in the cable operating direction, is described bellow. The free end of the brake lever is branched away two opposed splitting parallel plates separating in a direction of a rotation axis of the brake lever. The free end of the brake lever is rotatable between two opposed splitting parallel walls at an intermediate portion between both ends of the strut. A cable end nipple with a various flat portion, such as a partially disk-like shape, is positioned between the parallel plates constituting the free end of the brake lever, and columnar projections, projecting out from the respective flat side surfaces of a flat portion of the cable end nipple, is connected on the free end of the brake lever in the cable operating direction.
This structure has an advantage of minimizing the size of the mechanical actuating mechanism.
A method of hooking the columnar projections of the cable end nipple on the free end of the brake lever is described bellow.
The cable end nipple is rotated around the cable axis so that the flat side surfaces of the flat portion of the cable end nipple become parallel to the parallel plates of the brake lever. Such a conditioned cable end nipple is entered into the space between the parallel walls of the strut in a cable releasing direction so that the columnar projections push the brake lever to rotate in the same direction. The columnar projections are passed through a tip of the free end of the brake lever, thereby ending the rotation of the brake lever. Therefore the brake lever rotates back to return to an initial position. The brake cable is pulled in the cable operating direction to position the flat portion in between the free ends of the parallel plates so as to hook the columnar projections thereon making an engagement therebetween.
There exists a demand for minimizing the actuating mechanism in the brake lever rotation axis by shortening the columnar projections projecting from the flat portion of the cable end nipple. Hence, the thickness of the flat portion is designed as thin as possible, and the width of the parallel plates of the brake lever is designed to be a bit wider than the thickness of the flat portion. Furthermore, the width between the parallel walls of the strut is specified a minimum width necessary for passing the rotated cable end nipple through, i.e., the width being a bit wider than a dimension between the projected tips of both columnar projections.
Accordingly, when connecting the cable end nipple or hooking the columnar projections of the cable end nipple to the free end of the brake lever, if the two flat side surfaces of the flat portion of the cable end nipple are not pre-rotated around the cable axis readily and precisely parallel to the parallel plates of the brake lever, the parallel walls of the strut become obstacles preventing the cable end nipple from further proceeding into the space between the parallel walls. However, if the brake drum is fully covered, visual observation of the free end of the brake lever during the connecting operation often is a very difficult task. In such instance there is a concern of poor accessibility for connecting the brake cable.
An object of this invention is to make arrangements in the above-conventional brake cable connecting apparatus in order to improve a connecting operability of the brake cable. This invention attains the object of the improved operability by adding a feature of the cable end nipple to automatically be rotated and proceeded into a space reserved between the parallel walls of the strut simply by pushing the cable end nipple toward the space between the parallel walls in the cable releasing direction.
Another object of this invention is to improve the brake cable connecting operation after being positioned in the space between the parallel walls of the strut by eliminating the conventionally necessary horizontal adjustment of the cable end nipple to be specifically aligned with the connecting portion of the cable end nipple and the free end of the brake cable.